<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>

    #d1{
      width: 100px;
      height: 100px;
      border: 1px solid red;

      /*margin-top: 100px;*/
      /*margin-left: 50px;*/
      /*margin-bottom: 50px;*/
      /*margin-right: 50px;*/

      margin: 50px;
      margin: 50px 100px;
      margin: 0 auto;
      margin: 10px 20px 30px 40px;
    }

    #d2{
      width: 100px;
      height: 100px;
      border: 1px solid red;

      margin-top: 20px;
    }


    #s1{
      margin-left: 50px;
      margin-right: 50px ;;
    }
    #s2{
      margin-left: 50px;
    }


    #big{
      width: 200px;
      height: 200px;
      background-color: green;

      overflow: hidden;
    }

    #big > div{
      width: 50px;
      height: 50px;
      background-color: purple;
      margin-left: 50px;

      /* 当元素的上边缘和上级元素的上边缘重叠时,给元素添加上外边距会出现粘连问题,
         给上级元素添加overflow: hidden样式解决
      */
      margin-top:50px;

    }
  </style>
</head>
<body>

<div id="big">
  <div></div>
</div>
<span id="s1">span1</span>
<span id="s2">span2</span>

<div id="d1"></div>
<div id="d2"></div>
</body>
</html>